To most people, a coffee stain might not seem like much, but to German illustrator Stefan Kuhnigk, there’s hidden creatures inside every obscure, brown smudge. The self-confessed caffeine lover turns random coffee spillages into all sorts of weird and wonderful monster characters.

His routine to draw coffee stain started in 2011, while at a meeting at the advertising agency he works at, Kuhnigk accidentally spilled a cup of coffee on some of his report. Rather than throw the paper to the trash, Kuhnigk started to doodle on top of the dried spillage, filling in the missing shapes and lines to create his first coffee monster. Since 2011, he’s been creating one every day, and now has a collection of over 500 coffee critters.

Kuhnigk’s monster drawings range from sweet and adorable to evil and mischievous. From strange blobs with eyes and teeth to multi-headed brown splats, each kooky character visualizes the artist’s playful imagination. “I really enjoy every single one because I love creation and the determination or coincidence of the coffee hitting paper,” he reveals. “I try to see a monster, character, or figure in it and when I find something, I draw it.”